CN107380148B - A kind of electric vehicle brake torque comprehensive regulation method and system - Google Patents
A kind of electric vehicle brake torque comprehensive regulation method and system Download PDFInfo
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- CN107380148B CN107380148B CN201710625526.2A CN201710625526A CN107380148B CN 107380148 B CN107380148 B CN 107380148B CN 201710625526 A CN201710625526 A CN 201710625526A CN 107380148 B CN107380148 B CN 107380148B
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- 238000004364 calculation method Methods 0.000 claims description 3
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/171—Detecting parameters used in the regulation; Measuring values used in the regulation
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T8/00—Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force
- B60T8/17—Using electrical or electronic regulation means to control braking
- B60T8/172—Determining control parameters used in the regulation, e.g. by calculations involving measured or detected parameters
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- Transportation (AREA)
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- Control Of Driving Devices And Active Controlling Of Vehicle (AREA)
- Regulating Braking Force (AREA)
Abstract
The present invention relates to a kind of electric vehicle brake torque comprehensive regulation method and system, with the continuous increase of pedal travel, and when monitoring that wheel slip mutates, comprehensive regulation is carried out to braking moment, comprising: the estimation of tire-road frictional force, braking moment self adaptive control, braking torque distribution.Wherein, pass through speed and wheel speed etc., current wheel slip and slip rate difference are calculated in real time, in conjunction with preset tire model fitting function, front and back wheel slip rate error threshold and observer adjust gain etc., front and back tire-directly related variable of road surface friction force is estimated simultaneously, and then calculates current desired front and back wheel brake force square, is maintained at front and back wheel slip rate near ideal value.Front and back wheel braking moment approximation is distributed to front and back wheel motor braking torque and mechanical braking torque according to braking torque distribution coefficient-frequency curve.The present invention effectively improves the control for brake performance of vehicle electric system.
Description
Technical field
The present invention relates to electric vehicle brake control, in particular to a kind of electric vehicle brake torque comprehensive regulation method and
System.
Background technique
Braking ability is one of most important factor in active safety systems of vehicles.Automobile is provided with anti-lock braking system at present
(Antilock Brake System, ABS), makes vehicle be able to maintain best wheel slip in emergency braking, to optimize wheel
Tire longitudinal direction adhesive force simultaneously shortens braking distance.Meanwhile wheel lateral traction can also be optimized by control for brake, to keep good
Good vehicle handling quality.The promotion of braking system performance is further ensured the safety for making vehicle and driver and passenger.
And at the emergency braking moment, the difference bring influence of braking ability will be protruded more.Therefore, motor vehicle braking system is constantly promoted
Performance, have very strong engineering significance.
Braking moment regulates and controls as the key technology in motor vehicle braking system, has been a hot spot of research and difficult point.Due to
There are very strong non-linear relation between tire-road attachment coefficient and wheel slip, the accurate acquisition of numerical value has one
Fixed difficulty.Meanwhile the phenomenon that there are the Forwards of vehicle centroid in braking process, make the tune of vehicle front and back wheel braking moment
Control tool acquires a certain degree of difficulty.Braking system of electric car is made of motor braking and friction catch mixing, than orthodox car braking system
System is complicated, and increases the uncertain factor in braking system.Motor output torque has the advantages that accurate, quick response, rubs
Wiping brake output torque is larger but variation is slow.Therefore, motor braking can be used to make up friction catch dynamic response not
Foot stablizes slip rate near desired value, accelerates the receipts of slip rate to promote the dynamic response of braking system
Hold back situation.But the introducing of motor braking also increases the complexity of electric vehicle brake regulation.
A kind of existing " regenerating brake control method for electric car based on the ABS " (patent No.
201110260769.3) energy regenerating preferentially is carried out using motor braking power, but severity of braking is not considered." one kind is based on mostly about
Electric car regenerating brake control method under the conditions of beam " (patent No. 201510437923.8) with Brake energy recovery be set out
Point distributes regeneration torque according to severity of braking, calculates braking direct bearing torque not according to vehicle-state.It is " a kind of electronic
Automobile Electro-hydraulic brake control method and its control device " (patent No. 201310228662.X) select according to driver intention
A kind of braking mode is selected, energy energy is recycled using motor braking on the basis of guaranteeing brake safe, does not consider braking moment point
With problem.
Summary of the invention
The purpose of the present invention is to provide a kind of electric vehicle brake torque comprehensive regulation method and system, pass through tire-
Road surface friction force estimation, the self adaptive control of vehicle braking torque and braking torque distribution, improve the braking control of vehicle electric system
Performance processed.
A technical solution of the invention is to provide a kind of electric vehicle brake torque comprehensive regulation method, passes through pedal
When to electric vehicle brake, braking moment is according to pedal travel linear convergent rate；
When detecting according to the mutation of the wheel slip of speed and wheel speed calculation, comprehensive tune is carried out to braking moment
Control, comprising the following steps:
S1, estimated by tire-road frictional force, obtain tire-road frictional force variable estimated value
S2, braking moment self adaptive control is carried out, to calculate current desired according to the gain of preset controller
Front and back wheel brake force square Tbi, it is maintained at front and back wheel slip rate near ideal value；
The rule of the braking moment self adaptive control of setting are as follows:
In formula, r is radius of wheel, Φ (λi) be Burckhardt tire model approximate representation formula in regressor, λiFor vehicle
Wheel slip rate, v are speed, kiFor error feedback oscillator, the constant greater than zero, e are takeniFor front and back wheel slip rate error, i ∈ F,
R }, F represents front-wheel, and R represents rear-wheel；
S3, braking torque distribution: by the mechanical braking torque T of electric carMWith motor braking torque TEAccording to braking moment
TbiFrequency be allocated.
Preferably, the tire-road frictional force estimation in step S1, is by the way that observer is arranged, to front and back tire-road
The directly related variable θ of frictional forceiEstimated simultaneously:
θi=pFzi
μ(λi)=Φ (λi)pT
In formula, tire-road frictional force variable estimated value is obtained by observerγiIt is observer adjustment parameter, εiFor
Slip rate error threshold, eεiFor slip rate regulating error error,For t0Moment variable θiInitial estimate, μ (λi) be
Tire-road attachment coefficient, FziFor the normal load of tire, p is linear parameter relevant to coefficient of friction；
According to Lyapunov function
Wherein, J is vehicle wheel rotation inertia,
There are eεSo thatI.e.By Lyapunov Theory of Stability know observer be it is stable, then
Estimate variable θiNumerical value, further obtain the estimated value of the road surface friction force of front and back wheel.
Preferably, by the braking moment self adaptive control of step S2, make wheel slip under braking moment effect at
Exponential law converges near ideal value.
Preferably, when carrying out braking torque distribution in step S3, it is provided with filter
L=αM+αE+βM+βE
Wherein, αj,βj, j ∈ { M, E } is the weight system being adapted with braking torque distribution coefficient curve varying with frequency
Number, αMAnd αEIt is the weight coefficient of mechanical braking torque and motor braking torque amplitude, β respectivelyMAnd βEIt is mechanical brake respectively
With the weight coefficient of electromotor brake output torque variable quantity；
Braking moment TbiAfter wave filter, according to the curve by braking moment TbiApproximation distribution is electric to front and back wheel
Brake force square TEAnd mechanical braking torque TM。
Preferably, when carrying out braking torque distribution in step S3, by solving following formula
Braking torque distribution coefficient ρ (f) is obtained, to mechanical braking torque TMWith motor braking torque TEBy braking moment Tb
Frequency f be allocated；The braking torque distribution coefficient ρ (f) meets the requirement of discrete filter, and as close as pre-
The distribution coefficient ρ first defined*(f)；
Wherein, weight coefficient αj,βj, j ∈ { M, E } meets the following conditions:
In formula, tsIndicate that sampling step length, N indicate step number.
Preferably, in step S3 carry out braking torque distribution when, by the frequency partition of braking moment be low frequency, intermediate frequency and
High frequency section；So that motor braking torque T when high frequency sectionEUse ratio be higher than mechanical braking torque TM, and when low frequency section
Mechanical braking torque TMUse ratio be higher than motor braking torque TE。
The system that another technical solution of the invention is to provide a kind of electric vehicle brake torque comprehensive regulation, in use
State any one electric vehicle brake torque comprehensive regulation method；
The system includes: brake monitors, upper controller, lower layer's distributor, CAN network；It is transmitted according to CAN network
The car status information come, the brake monitors are calculated in real time and are monitored during brake-pedal travel is gradually increased
Whether current wheel slip mutates；
The brake monitors carry out the estimation of tire-road frictional force when monitoring that wheel slip mutates, and
Issue the instruction for driving the upper controller starting braking moment self adaptive control；
The upper controller is worked as according to tire-road frictional force variable estimated value and preset gain, calculating
Preceding required front and back wheel brake force square, is maintained at front and back wheel slip rate near ideal value；
Lower layer's distributor further distributes front and back wheel brake force square to electromotor brake and mechanical brake, will be according to pre-
Braking torque distribution coefficient-the frequency curve first defined distributes front and back wheel braking moment approximation to front and back wheel motor braking
Torque and mechanical braking torque.
Preferably, during by stepping on pedal to electric vehicle brake, wheel that the brake monitors detect
When slip rate, speed, vehicle wheel rotational speed data keep normal, proportional output motor braking moment is distinguished according to brake-pedal travel
And mechanical braking torque, motor braking actuator and mechanical braking actuator are passed to by CAN network, vehicle is carried out
Retarding braking operation；Upper controller described in period does not start.
Preferably, when the brake monitors detect car speed lower than threshold value, issue close upper controller and under
The instruction of Layer assignment device to stop the output of motor braking torque, and directly exports maximum mechanical braking torque, until vehicle reaches
To totally stationary state.
In conclusion electric vehicle brake torque comprehensive regulation method and system provided by the invention, upper layer is estimated simultaneously certainly
Suitable solution front and back wheel braking moment, lower layer dynamically distribute motor braking torque and mechanical braking torque in each wheel,
Stablize slip rate near desired value, makes full use of frictional ground force to be braked, effectively improve the system of vehicle electric system
Dynamic control performance.
Detailed description of the invention
Fig. 1 is electric vehicle brake torque comprehensive regulation system construction drawing；
Fig. 2 is tire-road attachment coefficient fitted figure；
Fig. 3 is braking system of electric car force analysis figure；
Fig. 4 is braking torque distribution charts for finned heat；
Fig. 5 is wheel slip response curve；
Fig. 6 is front wheel brake Torque distribution curve graph；
Fig. 7 is rear service brake torque distribution curve figure.
Specific embodiment
A kind of electric car composite braking torque comprehensive regulation method, uses electric car comprehensive regulation as shown in Figure 1
System, including brake monitors, the front/rear wheel braking moment adaptive controller in upper layer and lower layer's motor/mechanical braking torque
Distributor.When driver's pedal is braked, braking moment is according to pedal travel linear convergent rate.Meanwhile brake monitors root
According to speed and wheel speed calculation tyre skidding rate.Slip rate adjuster is opened if detecting slip rate mutation, to braking moment
Comprehensive regulation is carried out, wherein mainly including the estimation of tire-road moment of friction, wheel braking moment self adaptive control, and braking
Torque distribution link.
Specific regulation link is as follows:
S1. tire-road frictional force is estimated
For the non-linear relation between approximate representation tire-road attachment coefficient μ (λ) and slip rate λ, following institute is selected
Burckhardt (Burckhardt) tire model shown:
Wherein constant term ciIt is Burckhardt tire model fitting coefficient.
It, will be in Burckhardt tire model for the ease of subsequent Design of ObserverIt is linear that item carries out following parameter
Change processing
Wherein θiIt is linear parameter, ωiIt is weight coefficient.
Therefore, Burckhardt tire model can approximate representation are as follows:
μ (λ)=Φ (λ) pT+Δμ(t,λ) (3)
In formula, p is one group of linear dimensions, and Φ (λ) is regressor, Δμ(t, λ) is linearisation bring approximate error.
For dry bituminous pavement, under the attachment coefficient curve and Burckhart tire model that are fitted using the above method
Curve comparison is as shown in Fig. 2.It can be seen from the figure that fitting data is with Burckhart tire model data with very high
Degree of agreement is able to satisfy subsequent demand for control substantially.
Tire-road frictional force is directly related with brake force, and comprehensive by tire-road attachment coefficient and analysis of wheel vertical load
It closes and determines.Since tire-road attachment coefficient can not be obtained accurately, and front and back wheel vertical load in braking process not yet
Disconnected variation, therefore this method selection direct estimation tire-road frictional force replaces traditional tire-road coefficient of friction to estimate,
And it is defined as follows variable:
θi=pFzi,i∈{F,R} (4)
Wherein, p is linear parameter relevant to coefficient of friction, F in formula (3)ziFor the normal load of tire, before F is represented
Wheel, R represent rear-wheel.
Following observer is designed to variable θiEstimated with while being obtained the road surface friction force of front and back wheel
γ in formulaiIt is observer adjustment parameter, eiFront and back wheel slip rate error, ε are slip rate error threshold, eεiFor cunning
Shifting rate regulating error error,For t0Moment variable θiInitial estimate.
By selecting following Lyapunov (Liapunov) function
It can obtain using the Design of Observer method in formula (5), there are eεSo thatR is radius of wheel, i.e.,Be by observer known to Lyapunov Theory of Stability it is stable, can accurately estimate variable θiNumerical value, further
Obtain the size of front and back wheel frictional force.
S2. braking moment self adaptive control
Vehicle braking moment Overall Analysis is as shown in figure 3, corresponding kinetics equation is as follows:
V is speed, ω in formulaiIt is angular speed of wheel, TbiFor braking moment, λiWheel slip, r are wheel effectively half
Diameter, J are vehicle wheel rotation inertia, and i ∈ { F, R }, F represent front-wheel, and R represents rear-wheel, and M is vehicle mass.
Utilize vehicle tyre-road surface friction force estimated value, the design of vehicle braking torque adaptive control law are as follows:
K in formulaiFor the constant greater than zero, eiFor front and back wheel slip rate error.
By seeking first derivative to the front and back wheel slip rate in formula (7), the braking moment that can be obtained in formula (8) is adaptive
Under control law, the slip rate kinetics equation of wheel is evolved into
λi *For front and back wheel slip rate desired value, it can be seen that wheel slip in the brake force as shown in formula (8) from formula (9)
Exponentially rule is converged near ideal value under square effect, thus to greatest extent using road adherence come when shortening braking
Between and distance, improve the comprehensive performance of that motor vehicle braking system.
S3. braking torque distribution
Since electric car exists simultaneously two sets of braking systems of motor braking and mechanical braking, vehicle braking torque is being obtained
Adaptive control law after, need further to be designed the distribution method of braking moment.Motor braking is able to achieve energy
Recycling, and the bandwidth that torque responsive provides is faster than friction catch, therefore motor braking torque can be used to improve the dynamic of braking system
Step response.The response of mechanical braking torque is relatively slow, but braking effect is more stable and can ensure sufficient braking moment output.Cause
This, considers braking moment T in formula (8) during braking force distributionbFrequency characteristic, make motor braking torque TEThe height of centering
Frequency braking moment TbIt is more sensitive, mechanical braking torque TMTo low frequency TbIt is more sensitive.I.e. in braking moment TbWhen demand acute variation,
Use motor braking torque T moreE, and in braking moment TbWhen demand is steady, increase mechanical braking torque T appropriateMUse,
To improve the stability of braking moment output.
It is as follows to define braking torque distribution rule:
ρ in formula*For with braking moment TbThe relevant motor braking torque T of frequency fEWith mechanical braking torque TMDistribution coefficient.
As shown in figure 4, defining motor braking torque TEWith mechanical braking torque TMDistribution coefficient curve varying with frequency,
And by braking moment TbFrequency partition be low frequency, intermediate frequency and high frequency section.
Consider motor braking system and mechanical braking system actuator characteristics, be defined as follows shown in optimization problem:
First part is used to constrain mechanical braking system in formula (11), and second part is used to motor braking system
It is constrained.αMAnd αEIt is the weight coefficient of mechanical braking torque and motor braking torque amplitude, β respectivelyMAnd βEBrake output
The weight coefficient of moment variations amount.tsIt indicates that sampling step length, N indicate step number, is discrete system default variables symbol.
Definition of theorem Lagrange's equation as follows
Wherein, lLFor Lagrangian.
Local derviation is sought with single order optimal conditions and to formula (12), the discrete filter that can be shown below
L=αM+αE+βM+βE (13)
Choose suitable weight coefficient αj,βj, j ∈ { M, E }, in order to enable Torque distribution distribution coefficient ρ meets discrete filter
The requirement of device, and as close as distribution coefficient ρ predetermined in formula (10)*, be further defined as follows shown in it is non-thread
Property least squares problem:
Final braking torque distribution coefficient ρ (f) is obtained by solving formula (14), makes mechanical braking torque TMWith motor system
Kinetic moment TEBy braking moment TbFrequency be allocated.
Electric car is in braking process, and when driver's brake pedal, braking system is according to brake-pedal travel
Proportional output motor braking moment T respectivelyEAnd mechanical braking torque TM.Meanwhile brake monitors pass through speed v and four
The rotational speed omega of wheel, and current front and back wheel slip rate λ is calculated in real time.When slip rate, speed, the vehicle that brake monitors detect
When all data such as wheel speed are normal, braking moment adaptive controller does not start, motor braking torque TEAnd mechanical braking
Torque TMContinue to keep the linear ratio relation between brake-pedal travel, and is passed to brake command by CAN network
Motor braking actuator and mechanical braking actuator carry out retarding braking operation to vehicle.
With the continuous increase of pedal travel, when brake monitors monitor wheel slip λ mutation, braking moment
Adaptive controller starts to start.Brake monitor according to CAN network transmitting come car status information, such as speed v and four
The rotational speed omega etc. of a wheel calculates current wheel slip λ and slip rate difference e in real time, in conjunction with presetting tire model
Fitting function Φ (λ), front and back wheel slip rate error threshold εiAnd observer adjusts gain gammai, by following formula to front and back wheel
The directly related variable θ of tire-road surface friction forceiEstimated simultaneously.
θi=pFzi,i∈{F,R}
μ(λi)=Φ (λi)pT
The tire-road frictional force variable estimated value that braking moment adaptive controller is then further obtained according to observerAnd the gain of controller is preset, it is calculate by the following formula current desired front and back wheel brake force square Tbi, make front and back wheel
Slip rate is maintained near ideal value.
Lower layer's braking torque distribution device is further by braking moment TbiIt distributes to electromotor brake and mechanical brake.First
Braking torque distribution coefficient-frequency variation curve as shown in Figure 4 is defined, then chooses suitable weight coefficient according to formula (14)
αj,βj, filter as follows is finally arranged after obtaining optimal weight coefficient in j ∈ { M, E }
Braking moment TbiIt, will be according to braking torque distribution coefficient-frequency predetermined after filter in formula (17)
Curve is by front and back wheel braking moment TbiApproximation is distributed to front and back wheel motor braking torque TEAnd mechanical braking torque TM.When
Braking moment TbiWhen change frequency is lower, mechanical brake undertakes the most of braking moment of system, and motor braking undertakes braking moment
It is smaller.And work as braking moment TbiWhen change frequency is got higher, electromotor brake undertakes braking ratio and also increases accordingly.Braking moment is comprehensive
Regulating effect is closed as shown in Fig. 5~Fig. 7, in Fig. 5, when brake monitors detect front and rear wheel slip rate in 0.5 second Shi Fasheng
When mutation, start adaptive polo placement braking moment, by Torque distribution device by Torque distribution to electromotor brake and mechanical braking
Device controls vehicle deceleration.Subsequent front and rear wheel slip rate smoothly rises under the control of braking system and is maintained near 0.16,
Wherein front wheel slip rate rises very fast, just settles out after 0.16 fluctuation within a narrow range nearby, rear wheel slip rate fluctuate it is smaller, can
See that this method can be such that slip rate stablizes to desired value in a short time.Front and rear wheel braking torque distribution such as attached drawing 6,7 institute of attached drawing
Show, in front and back wheel Torque distribution, motor braking torque and mechanical braking torque are adjusted all in accordance with Torque distribution ratio dynamic.Front-wheel
Normal load is larger, while required braking moment is also larger, and motor output torque reaches maximum 200Nm.Brake force needed for rear-wheel
Square is smaller, and when braking moment variation rate is big, motor exports braking moment and is greater than mechanical braking torque.When required braking moment reaches
When to stable state, mechanical braking undertakes most of braking moment, and it is smaller that motor braking then undertakes braking moment.
In vehicle braking final stage, when brake monitors detect car speed lower than threshold value vsWhen, close brake force
Square adaptive controller and distributor stop the output of motor braking torque, and directly export maximum mechanical braking torque, until
Vehicle reaches totally stationary state.
It is discussed in detail although the contents of the present invention have passed through above preferred embodiment, but it should be appreciated that above-mentioned
Description is not considered as limitation of the present invention.After those skilled in the art have read above content, for of the invention
A variety of modifications and substitutions all will be apparent.Therefore, protection scope of the present invention should be limited to the appended claims.
Claims (8)
1. a kind of electric vehicle brake torque comprehensive regulation method, which is characterized in that
When by pedal to electric vehicle brake, braking moment is according to pedal travel linear convergent rate；
When detecting according to the mutation of the wheel slip of speed and wheel speed calculation, comprehensive regulation is carried out to braking moment,
The following steps are included:
S1, estimated by tire-road frictional force, obtain tire-road frictional force variable estimated value
S2, carry out braking moment self adaptive control, thus according to the gain of preset controller, calculate it is current desired before
Rear service brake torque Tbi, it is maintained at front and back wheel slip rate near ideal value；
The rule of the braking moment self adaptive control of setting are as follows:
In formula, r is radius of wheel, Φ (λi) be Burckhardt tire model approximate representation formula in regressor, λiIt is sliding for wheel
Shifting rate, v are speed, kiFor the constant greater than zero, eiFor front and back wheel slip rate error, i ∈ { F, R }, F represent front-wheel, and R is represented
Rear-wheel；
S3, braking torque distribution: by the mechanical braking torque T of electric carMWith motor braking torque TEAccording to braking moment Tbi's
Frequency is allocated；
In step S1 tire-road frictional force estimation, be by be arranged observer, it is direct to front and back tire-road surface friction force
Relevant variable θiEstimated simultaneously:
θi=pFzi
μ(λi)=Φ (λi)pT
In formula, tire-road frictional force variable estimated value is obtained by observerγiIt is observer adjustment parameter, eiFor front and back
Wheel slip error, εiFor slip rate error threshold, eεiFor slip rate regulating error error,For t0Moment variable θi's
Initial estimate, μ (λi) it is tire-road attachment coefficient, FziFor the normal load of tire, p is line relevant to coefficient of friction
Property parameter；
According to Lyapunov function
Wherein, J is vehicle wheel rotation inertia,
There are eεSo thatI.e.By Lyapunov Theory of Stability know observer be it is stable, then estimate
Variable θ outiNumerical value, further obtain the estimated value of the road surface friction force of front and back wheel.
2. electric vehicle brake torque comprehensive regulation method as described in claim 1, which is characterized in that
By the braking moment self adaptive control of step S2, restrain wheel slip exponentially rule under braking moment effect
To near ideal value.
3. electric vehicle brake torque comprehensive regulation method as described in claim 1, which is characterized in that
When carrying out braking torque distribution in step S3, it is provided with filter
L=αM+αE+βM+βE
Wherein, αj,βj, j ∈ { M, E } is the weight coefficient being adapted with braking torque distribution coefficient curve varying with frequency, αM
And αEIt is the weight coefficient of mechanical braking torque and motor braking torque amplitude, β respectivelyMAnd βEIt is mechanical brake and electricity respectively
The weight coefficient of brake output torque variable quantity；
Braking moment TbiAfter wave filter, according to the curve by braking moment TbiApproximation is distributed to front and back wheel motor braking
Torque TEAnd mechanical braking torque TM。
4. electric vehicle brake torque comprehensive regulation method as claimed in claim 3, which is characterized in that
When carrying out braking torque distribution in step S3, by solving following formula
Braking torque distribution coefficient ρ (f) is obtained, to mechanical braking torque TMWith motor braking torque TEBy braking moment TbFrequency
Rate f is allocated；The braking torque distribution coefficient ρ (f) meets the requirement of discrete filter, and as close as fixed in advance
The distribution coefficient ρ of justice*(f)；
Wherein, weight coefficient αj,βj, j ∈ { M, E } meets the following conditions:
In formula, tsIndicate that sampling step length, N indicate step number.
5. the electric vehicle brake torque comprehensive regulation method as described in claim 1 or 3 or 4, which is characterized in that
It is low frequency, intermediate frequency and high frequency section by the frequency partition of braking moment when carrying out braking torque distribution in step S3；
So that motor braking torque T when high frequency sectionEUse ratio be higher than mechanical braking torque TM, and low frequency section opportunity tool
Braking moment TMUse ratio be higher than motor braking torque TE。
6. a kind of system of electric vehicle brake torque comprehensive regulation, using electronic described in any one of claim 1-5
Automobile brake torque comprehensive regulation method, which is characterized in that the system includes: brake monitors, upper controller, lower layer point
Orchestration, CAN network；
According to CAN network transmitting come car status information, the mistake that the brake monitors are gradually increased in brake-pedal travel
Cheng Zhong is calculated in real time and is monitored whether current wheel slip mutates；
The brake monitors carry out the estimation of tire-road frictional force when monitoring that wheel slip mutates, and issue
Drive the instruction of the upper controller starting braking moment self adaptive control；
The upper controller calculates current institute according to tire-road frictional force variable estimated value and preset gain
The front and back wheel brake force square needed, is maintained at front and back wheel slip rate near ideal value；
Lower layer's distributor further distributes front and back wheel brake force square to electromotor brake and mechanical brake, will be according to fixed in advance
Braking torque distribution coefficient-frequency curve of justice distributes front and back wheel braking moment approximation to front and back wheel motor braking torque
And mechanical braking torque.
7. the system of electric vehicle brake torque comprehensive regulation as claimed in claim 6, which is characterized in that
During stepping on pedal to electric vehicle brake, wheel slip that the brake monitors detect, speed,
When vehicle wheel rotational speed data keep normal, proportional output motor braking moment and mechanical braking are distinguished according to brake-pedal travel
Torque passes to motor braking actuator and mechanical braking actuator by CAN network, carries out retarding braking behaviour to vehicle
Make；Upper controller described in period does not start.
8. the system of electric vehicle brake torque comprehensive regulation as claimed in claim 6, which is characterized in that
When the brake monitors detect car speed lower than threshold value, the finger for closing upper controller and lower layer's distributor is issued
It enables, to stop the output of motor braking torque, and maximum mechanical braking torque is directly exported, until vehicle reaches totally stationary shape
State.
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| CN108327702A (en) * | 2018-01-26 | 2018-07-27 | 东风汽车集团有限公司 | A kind of four-wheel wheel hub motor independence drive control method |
| CN110614984B (en) * | 2018-06-20 | 2022-04-29 | 华为技术有限公司 | Method and device for hybrid braking |
| CN111098838A (en) * | 2018-10-26 | 2020-05-05 | 北汽福田汽车股份有限公司 | Vehicle control method and device and vehicle |
| CN111252048B (en) * | 2018-11-30 | 2021-04-20 | 比亚迪股份有限公司 | Method and device for controlling vehicle brake, storage medium and vehicle |
| CN110282119B (en) * | 2019-06-18 | 2022-10-28 | 西安航空制动科技有限公司 | Airplane brake control method based on pedal deceleration rate control |
| CN110569610A (en) * | 2019-09-12 | 2019-12-13 | 珠海罗西尼表业有限公司 | Fatigue evaluation method and device for mechanical movement transmission gear train |
| CN111137263B (en) * | 2019-12-26 | 2022-11-18 | 的卢技术有限公司 | Vehicle braking stability control method and system |
| CN113561950B (en) * | 2020-04-28 | 2024-04-19 | 北京新能源汽车股份有限公司 | Stability control method and device for distributed driving electric automobile and electric automobile |
| CN111824095B (en) * | 2020-06-14 | 2022-07-05 | 长春理工大学 | Four-wheel hub electric automobile electro-hydraulic composite brake anti-lock coordination optimization control method |
| CN112579966B (en) * | 2021-03-01 | 2021-05-14 | 天津所托瑞安汽车科技有限公司 | Method and device for calculating ABS reference vehicle speed, electronic equipment and medium |
| CN115723742A (en) * | 2021-08-26 | 2023-03-03 | 比亚迪股份有限公司 | Vehicle travel control method, vehicle travel control device, and vehicle |
| CN113978470B (en) * | 2021-12-13 | 2024-01-12 | 郑州轻工业大学 | On-line quick estimation method for friction force between tire and road surface |
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| US9463873B2 (en) * | 2014-07-13 | 2016-10-11 | The Boeing Company | Vehicle braking system having braking control and skid reduction functions |
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